Answer:
Option third is True.
Explanation:
We have been given the exponential expression
The exponent 7/9 is with the variable m only, not on 3. Hence, option first is not correct.
Also rational exponent is 7/9. Hence, second option is also incorrect.
Now, we can rewrite the expressions as
Now, using the rule
Hence, 9 is the index
Therefore, option third is True.